Police investigating the murder of Pc Ronan Kerr have seized a "significant" haul of arms and arrested a suspect.
The arms, including Kalashnikov rifles, rocket launcher components and possibly Semtex explosive, were discovered last night in Coalisland, east Tyrone.
The suspect, aged 26, was detained in Renton, Dunbartonshire, today.
Pc Kerr, 25, was killed when a booby-trap bomb exploded under his car in Omagh, Co Tyrone, on Saturday.
News of the breakthrough emerged after nationalist leaders joined police in a symbolic show of unity at the Catholic police officer's funeral in the village of Beragh, County Tyrone.
The murder has been blamed on dissident republicans opposed to the peace process
Assistant Chief Constable Drew Harris described the arms haul as the "most significant in recent years".
It was discovered hidden in stolen cars at a garage.
A spokeswoman for Strathclyde Police said: "Strathclyde Police can confirm that a 26-year-old male was arrested at approximately 1.10pm on Main Street, Renton, Dunbartonshire.
"This arrest was made by Strathclyde Police officers in relation to an ongoing investigation led by the Police Service of Northern Ireland."
Mr Harris revealed the details of the arrest and the arms find at a police press conference in Belfast.
He said: "Detectives from Serious Crime Branch who are investigating Ronan's murder have made a significant discovery of arms and munitions - one of the most significant in recent years. It was made in Coalisland last night.
"Within the last two hours a man has been arrested in Dunbartonshire in Scotland in connection with the find of weapons at Coalisland.
"This 26-year-old suspect is being brought back to Northern Ireland for questioning.
"Colleagues from Strathclyde Police assisted PSNI detectives in the arrest operation."
He added: "The arms discovery was made in Coalisland last night and will form lines of inquiry into Ronan's murder and into dissident activity generally.
"The seizure was made in a garage unit on the Mountjoy Road.
"Inside the unit police officers uncovered a number of stolen vehicles and inside those vehicles a significant amount of arms and munitions.
"The haul included: four rifles, ammunition, timer power units, detonators, incendiary bombs, components for rocket launchers and other explosive devices, and a quantity of explosives, possibly Semtex.
"This investigation into Ronan's murder will continue in the coming days and weeks with the same determination and professionalism which resulted in last night's discovery.
"Everyone in our country is much safer today because these munitions have been taken out of circulation.
"They will now be forensically examined and provide new lines of inquiry for our investigators."
The senior officer added: "Hundreds of people attended Ronan Kerr's funeral in Beragh this lunchtime.
"At one level, it was heartbreaking. My heart goes out to Ronan's family.
"At another level, it was heartening to see so many ordinary decent people from so many different walks of life come to pay their respects to a young man who had his whole life and career in policing in front of him.
"Many of Ronan's colleagues from the Police Service of Northern Ireland attended the funeral. But many others were unable to attend because they have been working round the clock on the investigation into his murder."